Blue Line Question

Do the Blue Line cars recieve DC power thru both the contact shoes and the pantagraph or are they like New Haven Line cars which recieve DC power thru the contact shoes and AC power thru the pantagraph?

The Blue Line cars use 600vdc the power supplied is the same for the Pantograph on the roof and the Third rail shoes on the trucks.

The blue line never runs two power sources simotaniously. From Wonderland-Airport they used the pantograph with the overhead catenary. Once it is stopped at airport, the pantograph is lowered, and power is switched to the third rail for the rest of the trip.

Just for clarification the Blue Line has no way of running on the two power systems at the same time. The Blue Line #4 car has what is known as a change over group, which consists of two very large contactors that control the power supplied from the overhead catenary and third rail. These contactors are electrically interlocked so one cannot be energized while the other is in use. These contactors are wired in such a way that the switch the motorman throws to drop the Pantograph also switches these contactors over from one to the other. This is often the reason why when a train’s pantograph will not lock down at airport, operations has no choice but to take it out of service.